# Filed Under #cooperation

### Intergenerational reciprocity and restoration

In conservation, we often talk about intergenerational equity, which is the idea that we should behave sustainably out of fairness towards future generations. However, how we treat others often depends on how we have been treated ourselves. If previous generations have over-exploited the natural resources and behaved unsustainably, will that make us feel less inclined to behave sustainably for future generations? In Chia-chen Chang’s recent paper in Sustainability Science, we explored this question using an experimental common-pool resource game. An example of a common-pool resource game The paper is specifically interested in restoration, and the key innovation was to investigate...

### Homophily

Homophily is the principle that contact between similar people occurs at a higher rate than among dissimilar people (reviewed in McPherson et al., 2001). It is a long-established principle (see e.g., Byrne (1969), which has 1000+ citations), and is particularly well established for friendships, which have been shown to be homophilous for ethnicity, age, religion, education, and social values ([16,156–160] in Dunbar (2018)). ‘Baseline’ homophily occurs because of the demography of the potential relationship pool, and effects beyond that occur due to other factors not limited to personal preference. Homophily acts on a variety of different dimensions. The ‘Big 5’...

### Evolutionary game theory model with homophilic imitation

The purpose of this blog post is to replicate results from Vasconcelos et al. (2014) and use it to learn about the behaviour of this kind of model. I am interested in this model because it involves homophily: it is a social learning model, but the probability of imitation depends not only on the relative payoffs between the focal player and other but also on how similar they are in wealth. Code can be found on Github: vasconcelos-2014-playground. The model Consider a population of $$Z$$ individuals of which $$Z_R$$ are rich and $$Z_P$$ are poor. The rich and poor have...

### Using n-player relatedness to model the Modern Tragedy of the Commons

In this blog post, I will use the “Modern Tragedy of the Commons” as an example for how to use Hisashi Ohtsuki’s $$n$$-player generalisation of relatedness. In a recent experimental study in Science Advances, Gross and De Dreu (2019) described the Modern Tragedy of the Commons: if people can individually solve a problem by purchasing a solution that protects themselves only, then they may prefer that to contributing to a cheaper collective solution (Fig. 1). One recent example might be the trend among wealthy Californian home-owners to hire private firefighters to defend their property from wildfires exacerbated by climate change....

### Fixation probability of birth-death process

The goal is to understand where Eq. 2 of the Supplementary section of Sigmund et al. (2010) came from. We are considering a finite population within which individuals are pursuing different game-theoretic strategies. At each timestep, a pair of individuals is chosen at random, and they engage in a social learning process, where individual $$i$$ will adopt the strategy of individual $$j$$ according to a function that increases with difference in the payoff betweeen the two strategies $$P_j - P_i$$, $\frac{1}{1+\exp( -s (P_j-P_i) )}$ where $$0 \leq s < \infty$$ is the imitation strength parameter. Let’s say that we have...

### Understanding the neigbour-modulated inclusive fitness approach

The goal is to understand Equation 4.2 of Rodrigues and Kokko (2016). To understand the technique, I read through Taylor et al. (2007), and Taylor and Frank (1996), specifically examples 4, 4a and 4b. Very briefly, we begin with a matrix $$A = [w_{i,j} ]$$ whose elements represent the genetic contribution of class $$j$$ to class $$i$$. Then for some mutant genic value $$x$$, the fitness derivative is $\frac{dW}{dx} = \sum_{i,j} v_i \frac{dw_{i,j}}{dx} u_j$ where $$\mathbf{v}$$ is the left eigenvector of $$A$$ and is the reproductive values, and $$\mathbf{u}$$ is the right eigenvector of $$A$$ and is the class frequencies....

### Evolution of parochialism

Previously I was reading about identity in Singapore, and I found that the government project of creating a national identity is focused upon creating a cosmopolitan mindset (i.e. one of openness and tolerance of difference), and that this interacts in different ways with the two main groups of foreigners, the ‘foreign talent’ and the ‘foreign worker’. The literature review that I did there was focused upon the sociological literature and Singapore specifically. In this post I provide a summary of some reading that I have done on experiments investigating group identity using economic games. I’ve focused specifically upon parochialism in...

### Identity in Singapore, the Internet, and connections to game theory

The following is a literature summary that I undertook as part of my broader interest in modelling social systems, using identity in Singapore as a case study. I should preface all of this by saying that the ideas below are not ‘my own’ as such, but rather my attempt to synthesise the literature and opinions of experts in Singapore. Identity in Singapore Since independence, the Singaporean government has actively worked to construct a civic national identity for the country. Three main phases can be identified (Ortmann, 2009): (1) 1965-1980s, focused primarily upon the objective of economic growth, the idea of...

### Termite eusociality

Termites are eusocial by possessing two subfertile or sterile castes, the worker and the soldier. The consensus is that eusociality in termites is the result of a suite of factors (Thorne, 1997), though the relative importance accorded to each in the literature has shifted over time (Howard and Thorne, 2011). For the purpose of a quick review, I have not looked into mechanisms that appear to have been set-aside in the literature, such as asymmetric relatedness and cycles of inbreeding and outbreeding (cited in Howard and Thorne, 2011). Soldiers Soldiers are monophyletic for all extant termite taxa (citations in Howard...